The U.S. Federal Reserve and European Central Bank, among other central banks, have begun tightening stimulus unleashed to counter the fallout from the global financial crisis.

The BOJ appears to have recently reduced its purchases of government bonds. However Gov. Haruhiko Kuroda has said he would maintain Japan's barrage of deflation-fighting stimulus until a 2 percent inflation target is met.

The aim is to convince companies and consumers to spend more, helping to sustain faster growth.

The economy expanded at a 2.5 percent annual pace in July-September, suggesting the policies may be gaining traction.

Many are watching to see if Prime Minister Shinzo Abe will reappoint Kuroda as governor of the central bank when his five-year term ends in April.